Recently, organic EL devices have been attracting attention as illumination devices which replace incandescent lamps and fluorescent lamps, and many studies have been made concerning these organic EL devices. An organic EL device is configured such that organic EL elements are laminated on a substrate such as a glass substrate or a transparent resin film.
The organic EL element is configured such that two electrodes where at least one of them has light transmitting property face each other in an opposed manner, and a light emitting layer made of an organic compound is laminated between these electrodes.
An organic EL device is a self-luminous device and can emit light having various wavelengths by suitably selecting a material for forming the light emitting layer. Further, the light emitting layer is extremely thin compared to an incandescent lamp and a fluorescent lamp and emits light in plane and hence, the restriction imposed on the installation place is small.
The layer constitution of a typical organic EL device is shown in FIG. 21. The organic EL device 200 shown FIG. 21 is configured such that a transparent electrode layer 203, a functional layer 205 and a back surface electrode layer 206 are laminated on a glass substrate 202, and these parts are sealed by a sealing part 207. The organic EL device 200 adopts a so-called bottom emission type constitution where light is drawn from a glass substrate 202 side.
Further, the functional layer 205 is formed by laminating a plurality of films formed using an organic compound or a conductive oxide film. The typical layer constitution of the functional layer 205 is configured such that, as shown in an enlarged view of FIG. 21, the functional layer 205 includes, in order from a transparent electrode layer 203 side, a hole-injection layer 208, a hole transport layer 210, a light emitting layer 211, an electron transport layer 212, and an electron-injection layer 215.
In this manner, an organic EL device is manufactured by sequentially forming the above-mentioned layers on the glass substrate 202.
With respect to the layers described above, the functional layer 205 is a layer formed by laminating a plurality of thin films made of organic compounds and all thin films are formed into films by a vacuum deposition method.
That is, as described previously, the functional layer 205 is formed by laminating the plurality of thin films made of organic compounds and hence, it is necessary to perform the vapor deposition plural times to form the functional layer 205.
Further, the back surface electrode layer 206 is, in general, formed of a thin film made of metal such as aluminum or silver, and is formed by a vacuum deposition method in the same manner as the functional layer 205.
Accordingly, in manufacturing just one organic EL device, it is necessary to perform the vapor deposition many times.
The conventional vacuum deposition device can vapor-deposit only one kind of thin film. For example, while the functional layer 205 of the organic EL device is constituted of the hole-injection layer 208, the hole transport layer 210, the light emitting layer 211, the electron transport layer 212 and the electron-injection layer 215, in the conventional method, these layers are formed by using separate vacuum deposition devices.
Accordingly, in the formation of the films of layers of the conventional organic EL device, it is necessary to frequently perform works of conveying the substrate into and out of the vacuum deposition device. As a result, a work efficiency of the conventional method is low and there has been a demand for improvement of the formation of the layers of the organic EL device.
As a countermeasure to overcome this drawback, there has been proposed a vacuum deposition device where a plurality of thin film layers can be formed using one film forming chamber in patent documents 1 and 2.
In the vacuum deposition device disclosed in patent documents 1 and 2, three diffusion containers are disposed in a film forming chamber.
A plurality of evaporating parts are connected to each diffusion device, and vapor of film forming materials is supplied to each diffusion containers from the respective evaporating parts. Then, vapor of film forming material (hereinafter referred to as “film forming vapor”) is discharged into the film forming chamber from each diffusion container and a film is formed on a substrate.
In the vacuum deposition device disclosed in patent documents 1, 2, a plurality of thin film layers can be formed in one film forming chamber by selecting the diffusion container into which a film forming vapor is to be discharged.
Further, in the vacuum deposition device disclosed in patent documents 1, 2, a film forming material supplied to the diffusion container can be changed by switching the evaporating part to be used. That is, in the vacuum deposition device disclosed in patent documents 1, 2, a plurality of thin film layers can be formed in one film forming chamber.
In patent document 1, as a unit for grouping film forming materials, there is disclosed a method where film forming materials having similar evaporation temperatures or similar limit temperatures are formed into a group. That is, as to the vacuum deposition device disclosed in patent document 1 where a plurality of evaporating parts are connected to each diffusion device, an interesting observation is made with respect to which evaporating part is to be used and which film forming material is to be evaporated.
In other words, patent document 1 discloses the preferred combinations of the evaporators and the film forming materials.
The method disclosed in patent document 1 is characterized in that film forming materials are divided into groups depending on evaporation temperatures and limit temperatures thereof, and the film forming materials having similar evaporation temperatures are charged into any one of a plurality of evaporating parts which are connected to the same diffusion device and are evaporated.